nuclear winter

the general devastation of life, along with worldwide darkness and extreme cold, that some scientists believe would result from a global dust cloud screening out sunlight following large-scale nuclear detonations.

nuclear winter definition

A theory first put forward in 1983 predicting that a large-scale nuclear exchange would produce enough smoke and soot to lower the temperature of the Earth significantly. Subsequent calculations indicated that the climatic effects would be much less than had originally been claimed, leading to the use of the term nuclear autumn to describe the phenomenon.